A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric. Some balloons are used for decorative purposes, while others are used for practical purposes such as meteorology, medical treatment, military defense, or transportation. A balloon's properties, including low density and low cost, have led to a wide range of applications.
Historically party balloons were be have been mostly made of natural latex tapped from rubber trees, and were be filled with air, helium, water, or any other suitable liquid or gas. The rubber's elasticity makes the volume adjustable. Filling the balloon with air can be done with the mouth, a manual or electric inflator (such as a hand pump), or with a source of compressed gas.
Beginning in the late 1970's, some more expensive (and longer-lasting) foil balloons made of thin, inelastic, less permeable metalized plastic films started being produced. These balloons have shiny reflective surfaces and are often printed with color pictures and patterns for gifts and parties. The most important attribute of metalized nylon for balloons is its light weight, increasing buoyancy and its ability to keep the helium gas from escaping for several weeks. Foil balloons have been criticized for interfering with power lines.
Many novelty or party balloons are referred to as being manufactured of Mylar or metallized Mylar. More precisely, the material is a metallized BoPET (Biaxially-oriented polyethylene terephthalate) that is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation. A variety of companies manufacture boPET and other polyester films under different brand names. In the US and Britain, the most well-known trademarks are Mylar, Melinex and Hostaphan.
The prior art includes insulated hot air balloons used to carry five or more persons in a basket suspended below the balloon. The balloon in this prior art is filled with steam instead of hot air to produce the buoyancy in the atmosphere. Steam has twice the load-bearing capacity of air; however, it necessitates insulation to prevent condensation from forming on the interior of the balloon envelope. For this purpose, flock insulation is bonded to a light but sensitive carrier foil.
A membrane flock insulating material was used to construct an insulated steam balloon. More particularly, a light metallized base fabric in combination with a membrane flock insulating material captures a layer of air by means of vertically oriented raised fibers on the base membrane. This membrane with its spacing elements is known as the spacing layer. The gap is closed by a covering layer. The insulting effect is determined by the width of this space, the flock pattern and the surface characteristics of the spacing and covering layers. The membrane flock insulating material is purported to be extremely light, highly reflective, mildly heat-reflective, temperature-resistant, compressible, readily adaptable to individual requirements and easily optimized by means of adjusting the spacing gap and the number of layers. High compressibility is a fundamental requirement, since balloons are packed and transported after a flight.
The lightweight insulation in this prior art is situated on the interior of the envelope, where it is protected against the adverse effects of everyday handling; this insulation in turn protects the load-bearing envelope against the effects of high temperatures. Higher temperatures than usual are encountered on the inner surface of the insulating material, while the cooler exterior of the envelope radiates less heat. This prior art material does not have any relevance to the exterior surface, the appearance, the electrical conductivity or reflectivity of a balloon.
A problem with the prior art party balloons, particularly or foil balloons is the reflectivity seriously interferes with pictures being taken by photographers. This problem is particularly acute at parties because partygoers routinely take many pictures.
Another problem with metallized or foil balloons is that they may short-circuit various electric circuits. This concern is not an idle or academic issue. For example, on Mar. 10, 1945, a balloon descended in the vicinity of the Manhattan Project's production facility at the Hanford, CA Site. This balloon caused a short circuit in the power lines supplying electricity for the nuclear reactor cooling pumps. Although, backup systems did function properly the chain of events does illustrate the dangers.